Update to Rust 2018

- Fix deprecated Error::cause warnings and missing dyn
- Reset max_width
- Add rustfmt to Travis
- Run rustfmt on full codebase
 with `cargo fmt --all`
- Add rustfmt to Travis
- Complete migration to edition 2018
- Replace try! shorthand
- Use explicit `dyn Trait`

core/src/mercury/mod.rs

@@ -1,13 +1,13 @@
+use crate::protocol;
 use byteorder::{BigEndian, ByteOrder};
 use bytes::Bytes;
 use futures::sync::{mpsc, oneshot};
 use futures::{Async, Future, Poll};
 use protobuf;
-use protocol;
 use std::collections::HashMap;
 use std::mem;
 
-use util::SeqGenerator;
+use crate::util::SeqGenerator;
 
 mod types;
 pub use self::types::*;
@@ -95,7 +95,8 @@ impl MercuryManager {
     pub fn subscribe<T: Into<String>>(
         &self,
         uri: T,
-    ) -> Box<Future<Item = mpsc::UnboundedReceiver<MercuryResponse>, Error = MercuryError>> {
+    ) -> Box<dyn Future<Item = mpsc::UnboundedReceiver<MercuryResponse>, Error = MercuryError>>
+    {
         let uri = uri.into();
         let request = self.request(MercuryRequest {
             method: MercuryMethod::SUB,